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Re: [TowerTalk] Thrust bearings

To: Charlie Gallo <>
Subject: Re: [TowerTalk] Thrust bearings
From: Grant Saviers <>
Date: Sun, 09 Oct 2011 20:27:37 -0700
List-post: <">>
Rulon and Vespel are terrific materials and fantastic choices for a slow 
speed bearing, metal to plastic.  No stick slip, lowest coefficient of 
friction for rulon, thermally stable, no moisture absorption, high PV 
ratings, yada yada.

HOWEVER, a Vespel bearing for a 2" mast might cost more than the tower, 
rotator, mast, and antennas all together.  It is fantastic stuff but 
incredibly expensive.  I understand the DuPont patents have run out so 
there are knockoffs coming to market, but still quite expensive. Rulon 
is somewhat cheaper but still has an impressive price.

How about Nylon MDS as a alternative - molybedenum disulfide filled 
nylon has good wear and UV resistance and is inexpensive.  I've bought 
2" thick plate on ebay at very low prices e.g. $40/sq ft.  It would make 
a good radial bearing and maybe with some engineering a combined 
radial/thrust bearing, which if the thrust load exceeds the rotator 
capacity, what is needed.  Otherwise, use the rotator for thrust and 
have just a nylon MDS sleeve bearing to handle the top of tower radial 
load.  Bore a hole 0.025" or so oversize the mast od, drill a bolt 
pattern to fit the top plate and install.  Might be a good idea to 
smooth up the galvanizing where it contacts the nylon.

Simple, cheap, no maintenance, no rust, no discussion of grease.

Grant KZ1W

On 10/9/2011 7:55 PM, Charlie Gallo wrote:
> Hey Gang,
> Reading the Nth thread on lubing thrust bearings, and just had a thought - 
> would it be a good idea to design a thrust bearing that works based upon an 
> 'ultra high molecularly weight filled self lubricating plastic" (aka 
> something like a filled teflon - or rulon or even vespel) - nothing to ever 
> rust/lubricate, and they can take decades of low to medium speed 
> rotation/sliding - heck, in theory, if your mast was truly round, you could 
> just have 3 or 4 pressure blocks, and it just rides on that
> BTW, for that matter, if you could assure it stays WET (not dry, WET), I'd 
> bet a lignum Vitae bearing would be about perfect for a tower thrust bearing

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